Time switch



Apnl 6, 1937. F. w. HOTTENROTH, JR., ET AL 2,076,371

TIME SWITCH Filed May 29, 1934 2 Sheets-Sheet 1 Inventors: Frederick WT'lottennoth Jr: WaIterFESIanQhar-d, GeoPcgeW. Sprenger:

Their" Attorney.

April 1937- F. w. HVOTTENROTH. JR.. ET AL 2,076,371

TIME SWITCH Filed May 29, 1934 2 Sheets-Sheet 2 \llllllllll lfiventor 5 MM 15 II/ll, Frederick W. HottenrothJr; AUGUST Walter Blanchard, fieorgeW-Spvenger, by 8 Patented Apr. 6, 1937 UNITED STATES PATENT OFFICE 'rnua swrr'on Frederick W. Hottenroth, Jr., Lynn, Walter P. Blanchard, South Hamilton, and George W. Sprenger, Lynn, Mass., assignors to General Electric Company, a corporation of New York Application May 29, 1934, Serial No. 728.124

5 Claims.

rangements of the switch blades, themselves, as

well as arrangements for accurately setting the timing element.

It is an object of our invention to provide an arrangement for accurately setting the time element and checking the time of operation of the time switch.

Another object is to provide an arrangement for quickly, conveniently, and accurately setting an astronomical time switch according to the day of the month and year and for locking the mechanism to maintain the proper relationship between diurnal and annual motions.

Still another object of our invention is the provision of a switch-actuating arrangement by means of which the energy for actuating the switch may be supplied by the timing motor and stored prior to the time of operation of the switch blades to permit an accurately-timed operation of the switch blades with a wiping snap action precisely at the desired instant.

Other and further objects and advantages of our invention will become apparent as the description proceeds.

The features of our invention which are believed to be novel and patentabie will be pointed out in the claims appended hereto. A better understanding of our invention, itself, however, may be obtained by referring to the following description taken in connection with the accompanying drawings.

In the drawings, Fig. 1 represents a front elevation with the cover removed of acommercial form of our time switch; Fig. 2 is a perspective exploded view of the time switch mechanism shown in Fig. 1; Fig. 3 is a perspective exploded view of the switch blade mechanism shown with the contacts in the open position; Fig. 418 an enlarged view of a portion of the astronomical dial of such a switch; Fig. 5 is a detail view of a contact operating cam employed'in the device; and Fig. 6 is a sectional view of a hollow- V lamp post or electric system pole showing our time switch mounted therein.

In an astronomical time switch, it is necessary to provide a member which rotates at the rate of once a year as well as a member which rotates 5 once a day. The former varies the time of setting for different seasons of the year in accordance with daylight variations, and the latter establishes the off and "on" operations from day to day. In our device, the mechanism for performing these operations may, if desired, be similar to that shown in United States Patent No. 1,891,946, December 27, 1932, Porter. In such a time switch a high-speed synchronous mtor may be and preferably is employed as the timing and driving element.

The commercial switch represented in Fig. 1 is a form adapted for mounting on poles used for supporting street lamps, electric wire systems and the like and is arranged for maximum compactness. The casing of the switch is shaped to conform to the shape of the pole within which it is mounted, making it unobtrusive and highly suitable for use in residential districts. Having circular front and back surfaces, the casing may be mounted either inside or outside the pole. The form of switch shown is contained in a casing x 8% exclusive of the terminal chamber and only 1%" in radial thickness. Obtaining the large gear reduction required in an astronomical time switch together with a great accuracy of operation, facility of very accurate setting, and convenience of adjustment in an operable timeswitch of the size and-compact construction mentioned and illustrated are believed to represent a considerable improvement with respect tosimplicity, accuracy, and cost of this type of device.

The switch structure is assembled in a casing ii, the cover of which has been removed. The center portion iii of the back wall of the casing II is made cylindrically concave to conform tothe shape of the poles in which the devices are usually mounted, and the curved edges 9 of the end walls are made substantially concentric with the cylindrical portion III of the back wall to permit closing the casing II with a curved plate cover (not shown). are so shaped and located in the casing as to obtain maximum utilization of the available space.

For convenience in manufacture and assembly, the mechanism is composed of several distinct parts forming self-contained units. The switch contact mechanism ii in which the actual mak- The elements of the .switch ing and breaking of an electrical circuit takes place is mounted in the upper portion of the casing I The dial unit l3 serving as the switch contact controlling and time-indicating mechanism is mounted in the center of the casing II and a speed reduction unit I4 is mounted in the lower right-hand corner of the casing H and supports a constant-speed driving mechanism |5 placed in the lower portion of the casing The constant-speed driving mechanism IS in the device shown is a self-starting synchronous motor of the general type describedjn United States Patent No. 1,495,936, May 27, 1924, Warren.

Although the unit l4, which for convenience in manufacture is assembled as a separate unit, is here termed a speed reduction unit, the entire reduction of speed required does not take place in this unit but merely a reduction in speed from one revolution per minute to one revolution per day, the synchronous motor unit l5 having contained therein suitable gearing for speed reduction from the synchronous speed of an alternating current electrical system to which the apparatus may be connected to a speed of one revolution per minute. The dial unit l3 contains the gearing for displacing a calendar dial one revolution during a year relative to a 24-hour dial.

The dial unit I3 is similar to that disclosed in the above mentioned Porter patent and includes a 24-hour dial IS, a calendar dial or. a SSS-day dial l1, and arms I8 and I9 carrying adjustable fingers 20 and 2i (Fig. 2). The fingers 20 and 2| engage pins 22 and 23 of the switch blade mechanism |2 to operate the switch mechanism in a manner to be described hereinafter. The angular positions of the arms I8 and I! with respect to the 24-hour dial |6 vary during the course of the year for the purpose of altering the time of day at which the switch is opened and closed. The mechanism for varying the positions of the arms l8 and I9 does not form part of the present invention and it will, therefore, be described only briefiy.

It will be apparent, since the slotted member 24 is fixed 'to the 24-hour dial l6 by rods 25, that radial motion of the pins 26 and 21 connected to arms I8 and I9 through links 28 and 29 will larger number of teeth in the same ratio might, of course, also be employed for these gears. Since pinion 34 engages both gear 32 and gear 33, the gear 32 is rotated through an angle corresponding to 364 teeth for each revolution of the gear 33 which has 364 teeth. This angle corresponds to 364/365 of a revolution or 1/365 of a revolution less than gear 33. In other words, the relative speed of gear 32 with respect to gear 33 is 1/365 the speed of gear 33 and 365-day dial makes one revolution relative to 24-hour dial l6 for every 365 revolutions of dial I6.

When initially placing the switch in operation, it will, of course, be necessary to set the slotted member 24 at an angular position with respect to the cams 36 and 3| and the 365-day dial |l corresponding to the time of the year. The dial I1 is graduated exactly in days of the common year as will become more apparent from Fig. 4 showing a portion of the dial for the month of August having thirty-one days. The graduations cooperate with a pointer 35 carried by slotted member 24, permitting 'the device to be set exactly at the day on which it is placed in operation.

In order to set the calendar device of the apparatus, that is, the portion including the slotted member 24 and the dial it is necessary temporarily that the dials I6 and Il may be rotated with respect to one another manually, independently of the speed relation fixed bythe gears 32 and 33 and the pinion 34. For this purpose, the pinion 34 may be mounted movably radially or axially to permit temporary disengagement. In the arrangement illustrated the pinion 34 is mounted to permit axial movement but is outwardly biased to the normal position by means of a spring 36. The invention is, of course, not limited to this precise arrangement. When it is desired to set the calendar device, the idler pinion 34 is pressed inward (Fig. 1) against the spring 36 (Fig. 2) to disengage the teeth of gear 32, and the idler pinion 34. When the calendar device has been properly set, the pinion 34 is released and gears 32 and 33, and likewise dials I6 and H, are locked in the proper relative position. This arrangementobviates the necessity for a slidable connection such as a friction cause variation in the angular positions of arms clutch for setting purposes in the gear reduction I8 and IS with respect to 24-hour dial l6. The between dials l6 and I1 radial positions of pins 26 and 21, in turn, are controlled by the rotation of cams 30 and 3|, which are fixed to 365-day dial H. The cams 30 and 3| are, of course, so shaped that the variations in angular position of the switch-operating fingers 20 and 2| with respect to time graduations on the 24-hour dial l6 will vary throughout the year in accordance with variations in the time of rising and setting of the sun or the variations in time of daylight. When placing the time switch in service, it is, of course, necessarythat the slotted member 24 controlling the positions of the arms l8 and |9 shall have the proper angular position with respect to the cams 30 and 3| and the 365-day dial H.

The speed reduction from one revolution per day of the 24-hour dial |6 to one, revolution in 365 days of the 365-day dial I1 is obtained by means of the gear wheels 32 and 33 engaging an idle pinion 34. The gear 32 mechanically connected to the 365-day dial H has 365 teeth and the gear 33 mechanically connected through hollow shaft 35' to slotted member 24 and the 24- hour dial "S has a number of teeth'difiering by one from 365, in the present case 364 teeth. A

and thereby overcomes the possibility that any slippage in the connection during operation may result in a change in the proper calendar setting of the device.

The switch-contact mechanism |2 is so arranged that opening or closing of the switch through contacts 31 and 38 will take place with a wiping action and will occur very rapidly or with a snap action at the precise moment for which the device is set. To this end the switch contacts 3'! and 38 are mounted on suitable pivoted switch arms 33 and 40, the positions of which are controlled by cams 4| and 42 mounted on a shaft 43 carrying the plate 44 in which are set the pins 22 and 23 which are engaged by the fingers 20 and 2| of the switch-controlling mechanism l3. The plate 44 may, if desired, carry the symbols oil'' and on, the uppermost of which indicates the condition of the switch. The switch arms 39 and 40 are biased to a downward position by relatively stifl' springs 45 and 46.

If desired, the portion 31 of the switch arm 40 may consist of a spring strip to insure good contact without binding between contacts 31 and 38. The connections to a circuit to be controlled are made by means of flexible conductors l and 8 connected at one end to the switch arms 3 9 and 40, respectively, and at the other end to sleeve type terminals (not visible) ,in the terminal chamber 6 (Fig. 1) which permit line conductors to be inserted through insulating bushings into the terminals. The switch arms 39 and 40 are pivoted on a shaft 4, preferably insulated or of insulating material, and are insulated from each other and from the casing 10 and supporting bracket by means of insulating washers 3.

Preferably, cam followers 39,, and 40' are interposed between switch arms 39 'and 48 and cams 4| and 42. The cam followers 39 and 49' may, if desired, take the form of disks rotatably mounted in the switch arms. In the apparatus illustrated, the cam followers are dumbbellshaped members with disk-shaped heads. The cams and cam followers may satisfactorily be composed 'of a plastic material, or a fibrous material with plastic binder, which serves to insulate the switch arms from each other, to minimize noise and friction, and to make for durability.

As the 24-hour dial l6 revolves, it carries with it the switch-operating fingers 20 and 2| so that, once per day atthe time of the day for which the apparatus is set, the finger 20 engages one of the pins 22 to open the time switch by separating contacts 31 and 38, and once per day the finger 2| engages one of the pins 23 to close the time switch by bringing the contacts 31 and 38- together.

The cams 4| and 42 are each shaped with a portion 41 of gradually increasing radius, a. pormake the angle subtended by cam portion 41 approximately equal to the sum of the angles subtended by portions 48 and 49. In the apparatus shown, the cams 4| and 42 are provided with duplicate portions 41, 48', and 49, corresponding to the portions 41, 49, and 49, the plate 44 is provided with two pins 22 and two pins 23 for the opening and closing operations, respect.

corresponds to a complete cycle of opening and closing operations, but it will be understood that the invention is not limited to this precise arrangement. For example, the invention obviously includes an arrangement in which the cams 4| and 42 are shaped with the portion 41 immediately following the portion 49 so that a complete revolution of the cam would correspond to a complete operating cycle, or with a plurality of duplicate portions so that a complete revolution of the cam would correspond to several operating cycles.

The shape of the cams and the presence of the biasing springs 45 and 46 permit the energy for operating the switch blades to be supplied gradually by the driving motor l5 as the fingers 20 and 2| first come into engagement with the pins 22 and 23, respectively, and to be stored in the tively, and a half revolution of cams 4| and 42 spring 45 or 46 until the'instant at which the switch is to be operated when the energy is quickly released by one or the other of the spring 45 or 46 to cause accurate operation of the switch at the desired time. For example, when the finger 20 comes into engagement with the pin 22, it gradually rotates the plate and the cams 4| and 42 as the 24-hour dial I6 rotates. The contacts 31 and 38 are initially together and the switch blade 46 is in its lowest position since the cam follower 48' is at the portion of minimum radius of the cam 42. As the plate 44 is rotated in a counterclockwise direction, the cams 4| and 42 both raise the cam followers 39 and 40' and, consequently, the switch arms 39 and 40, extending both of the springs 45 and 46. Since the switch arms 39 and 48 rise together, there is no change in the relative positions of contacts 31 and 38.

. At the precise moment for which the switch is set, however, the cam 4| has been rotated to the position at which the cam follower 39 starts to ride over the point 50 between the portion 41 of gradually increasing radius and the portion 48 of abruptly decreasing radius. The cam follower 40, however, is at, this moment at the beginning of the portion 41 of gradually increasing radius of the cam 42. At the moment when the cam follower 39' rides over the point 58 of the cam 4|, the force of the spring 45 pressing the cam follower 39' down against the portion 48 of the cam tends to drive the cam forward since the portion 48 is of abruptly decreasing radius. Consequently, the energy stored in the spring 45 is abruptly released, causing the cams to be rotated very rapidly to the point at which the cam follower 39' rests in the position 5| of minimum radius of the cam 4|. While this abrupt rotation of the cams is taking place, the arm 39 has, of course, been permitted to drop rapidly, snapping the contact 38 away from'the contact 31 and opening the switch. Since during this period, the cam follower 40 of the switch arm 40 has been riding over the initial part of the portion 41 of very gradually increasing radius of cam 42, the position of switch arm 40 and contact 31 has "been virtually unchanged.

As the switch has opened, the plate 44 has been rotated ninety degrees, and the pin 23 is in po sition to be engaged by the finger 2| shortly before the time arrives for the closing operation of the switch. A similar operation to that just described then takes place and both switch arms 39 and 40 are again gradually raised together against the tension of their respective springs 45 and 46 until the cam follower 48' rides over the point 52 of the cam 42 causing the switch arm 48 to drop abruptly from the opened position shown in Fig. 3 to the closed position shown in Fig. 2. It will be seen, therefore, that both the opening and the closing operations take place with a snap action and that a wiping contact is made.

As has already been explained, the 365-day dial I1 is provided with graduations showing each day of the year so that the day dial |1 may be set accurately to the precise day. An arrangement is also providedwhich permits the time dial to be set at the exact time of day by use of a micrometer dial graduated in minutes.

As has already been mentioned, the shaft 53 of the synchronous-driving unit |5 rotates at one revolution per minute and this speed is reduced through the reduction unit H to a speed of one revolution per day at the gear 54, which is mechanically connected through hollow shaft 35 to the slotted member 24 and the 24-hour dial |6. The speed reduction unit |4 consists of a train of gears'including a gear 55 which rotates at an intermediate speed, namely, one revolution per hour. The gear 55 is mounted on shaft 56 carrying a dial 51 graduated in'even minutes. For

clarity in the drawings, the unit graduations are not shown in Fig. -2. These, however, are apparent in Fig. 1 and the graduations cooperate with an index 58 formed in the edge of an open- 5 ing in the top plate of the speed reduction unit H as shown in Fig. l.

For the purpose of setting the device to the proper time of the day or for checking the time of operation of the switch, means are provided on shaft 56 such as a knob or slot 59, to facilitate manually rotating shaft 55. The 24-hour dial I6 may be rotated by means of a screw driver inserted in the slot 59 cut in the upper end of shaft 56 or by manually rotating the shaft 55 in any other suitable manner.

It will be seen that the 24-hour dial I6 is graduated in hours and fractions of an hour but the exact minute setting is obtained by observing the dial 5! as it rotates past the index 58.

2 If it is desired to check the time of operation of the switch, the shaft 56 is rotated slowly until the switch snaps open or shut and the time for which the device is set to operate is read from dial 51 by means of the index 58. Slight changes in the time setting may be made by adjusting the positions of the fingers and 2| on the arms 3 and IS.

in order that the minute adjustment of the dials may be made without manually driving the motor 15, a differential ratchet is provided consisting of a multiple panel plate 80 of spring material carried on shaft 56 engaging one face of the gear Bl forming part of the gear train of the reduction unit It and having a plurality of slots 62 therein. The panel plate 60 is provided with a plurality of prongs 63 pressing against the face of the gear SI and adapted to drop into the slots 62 as the shaft 56 is rotated in a counterclockwise direction. Preferably, the number of prongs 63 and the number of slots 62 are so chosen that one number will not be divisible by the other. If the numbers also do not have a common divisor a finer adjustment may be obtained for a given number of prongs or slots. For example, in the arrangement illustrated, the spring member 60 is provided with six prongs and the gear 5| with nineteen slots. Consequently only one prong drops into a slot at any one time and an action is obtained which permits setting the dial to the nearest half-minute. The drive permits relative rotation in only one direction, that is, the shaft 56 and the dial 51 may be moved in a counterclockwise direction which corresponds to a forward or clockwise movement of the dial Hi. The arrangement, however, prevents any slippage between the gears GI and the shaft 55 when the gear 6| is driven by the synchronous motor unit 15 so that there is no danger of a temporary or continued failure of the drive between the motor I5 and the hour-dial l6 which would result in a loss of time and an incorrect setting of the time switch during its normal operation. The maximum backlash is 360 degrees divided by the least common multiple of the'numbers of slots and prongs. With the number of slots and prongs chosen, there are 6 x 19 or 114 angular positions for each revolution of the minute dial 51 at which one of the prongs drops into one of the slots and insures positive drive. Therefore, even if the friction between the pronged member ill and the gear Bl should fail, positive drive from motor l5 to dials l6 and I! by engagement of one of the prongs with one of the slots would be insbred within little more than half a minute and the setting of minute dial 51 would be retained to an accuracy of 60/ 114 minutes in a year or one part in nearly a million.

Fig. 6 illustrates the manner in which our time switch may be mounted inside a hollow pole. Such poles as used in connection with electric street lighting and electric power systems commonly consist of an outer casing'll and an inner strengthening pipe I2. To facilitate installing and removing the time-switch an opening is left in the outer casing H of the pole, which may be closed by a cover 13. The time switch casing l I may be fastened in place in any desired manner, as for example, by means of a strap surrounding the strengthening pipe 12 and attached at its ends to the time switch casing ll. Obviously, if desired the time switch may also be mounted upon the outside of a pole in the same manner as here shown fastened to the strengthening -pipe 12.

-In accordance with the provisions of the patent statutes, we have described the principle of operation of our invention together with the apparatus which we now believe to represent the best embodiment thereof, but desire to have it understood that the apparatus shown and described is only illustrative and that our invention may be carried outby other arrangements.

What we claim as new and desire to secure by Letters Patent of the United States, is:

1. A switch comprising in combination, a pair of pivoted switch arms, a pair of contacts carried thereby, directed toward each other and arranged to make a wiping contact when said switch arms swing toward each other, a pair of cam followers, each mounted on one of said switch arms, a pair of rotatable cams, each adapted to engage one of said cam followers, resilient means tending to rotate each of said switch arms in' such a direction as to cause said cam followers to bear against the corresponding cams, a common shaft supporting said cams, means periodically engaging said shaft to rotate the same a part of a revolution, each of said cams being shaped with a portion of gradually increasing radius followed by a portion of abruptly decreasing radius followed in turn by a portion of radius increasing to the minimum radius of said first mentioned portion, said cams beingso arranged that the cam follower of one rides over the end of the first mentioned increasing radius portion of the cam to the portion of abruptly decreasing radius substantially as the cam follower of the other cam rides along the beginning of the first mentioned increasing radius portion of its correspondingcam and vice versa, whereby both of said switch arms are rotated together until the cam portion of abruptly decreasing radius is reached'when the energy stored in one of said resilient means serves to assist in causing rapid rotation of said cam shaft as one of said cam followers rides down said cam portion of abruptly decreasing radius and one of said switch arms is abruptly rotated toward said.

cam shaft, said contacts being somounted on said switch arms that, when one cam follower rides down the cam portion of abruptly decreasing radius, the contacts are snapped apart and, when the other cam follower operates in 9. corresponding manner, the contacts are snapped together.

2. A switch comprising in combination, a pair of pivoted switch arms, a pair of contacts carried thereby, a pair of mechanically connected rotatable cams, resilient means tending to rotate each of said switch arms toward said cams,

means for periodically rotating said cams a fraction of a revolution, each of said cams being shaped with a portion of gradually increasing radius followed by a portion of abruptly decreasing radius followed in turn; by a second portion of increasing radius, said cams being so arranged that one of said switch arms rides over the end of the first mentioned increasing radius portion of one cam to the portion of abruptly decreasing radius substantially as the other switch arm rides along the beginning of the first mentioned increasing radius portion of the other camand vice versa, whereby both of i said switch arms are rotated together until a cam portion of abruptly decreasing radius is reached and the energy stored in one resilient means serves to assist in causing rapid rotation of said cam shaft as one of said switch arms rides down said cam portion of abruptly decreasing radius, said contacts being so mounted on said switch arms that, when the arm rides down 20 the cam portion of abruptly decreasing radius,

the contacts are snapped apart and, when the other switch arm operates in a corresponding manner, the contacts are snapped together.

3. A switch comprising in combination, a pair of movable switch arms, a pair of contacts carried thereby, resilient means biasing each of said switch arms in a given direction, means for'moving both of said switch arms simultaneously in opposition to their resilient biasing means, thereby storing potential energy, means for abruptly releasing one of said switch arms and utilizing the released potential energy to cause an abrupt relative motion between said switch arms, means for abruptly. releasing the other of said switch arms. after potential energy has again been stored in both of said resilient means and causing relative motion of the opposite sense between said switch arms, said contacts being so mounted on said switch arms that, when the said switch arms move toward each other, the contacts are snapped together and, when the switch arms move away from each other, the contacts are snapped apart 4. A switch comprising in combination, a pair of movable switch arms, a pair of contacts carried thereby and each facing in a direction perpendicular to its direction of movability resilient means biasing each of said switch rms in a given direction, means for moving both of said switch arms simultaneously in opposition to their resilient biasing means, thereby storing potential energy, and means for abruptly releasing one of said switch arms and utilizingthe released potential energy to cause an abrupt relative motion between said switch arms, whereby separation and touching of said contacts take place with a wiping snap action.

5. A switchmomprising in combination, a pair of movable switch arms, a;,pair of contacts carried thereby and each facin gdn a direction perpendicular'to its direction of movability, whereby separation and touching of said contacts take place with a wiping action, means for moving said switch arms together in a given direction, resilient means opposing the motion of one of said switch arms and storing potential energy as said arm is moved, and means for abruptly releasing said latter switch arm to produce a snap action in the relative motion between said switch arms and said contacts.

FREDERICK W. HO'I'IENROTH, JR. WALTER P. BLANCHARD. GEORGE W. SPRINGER. 

